My patent application Ser. No. 14/280,605 and my patent application Ser. No. 14/821,778 teach a number of aspects of capturing and processing tonemapped HDR images, particularly for real-time video capture. Given that all known methods of tonemapping that produce high-quality tonemapped HDR, images are rather computationally expensive, there is an unmet need for improving the performance of this tonemapping so as to enable processing of higher resolutions and higher frame rates, in particular on affordable and compact mobile devices such as smartphones and hand-held cameras.